blood type diet

The blood type diet is based on the belief of naturopath
James D'Adamo that one's diet should be determined by one's blood type. Like
many self-confident mavericks before him, D'Adamo appealed to intuition for his brainstorm
("over the years, he recognized that each of the 4 blood types thrived on
certain foods and physical activities") and anecdotes rather than
controlled studies to support the validity of his ideas. His son, also
a naturopath,
Peter J. D'Adamo (whom the rest of this entry is about) is a fruit that did not fall far from
the tree. He has written several books, and travels the world promoting the
blood type diet.

There is no
reasonable scientific basis for the claim that blood type should determine
one's diet, though Peter claims to have
collected "over 1,000 scientific articles on blood types and their
correlations to disease, biochemistry, nutrition, and anthropology."*
Even so, he's never done a controlled study on blood type diets. Yet, he
claims that blood type
determines body chemistry to such an extent that those with type A blood
should go vegetarian and meditate, those with type O should eliminate grains
and do aerobics. He suggests similar unscientific diets for types B and AB.

The four human blood groups are defined by the type of glycoproteins — confections of sugar and protein — found on the surface of red blood cells and other cells.... A gene known as ABO helps construct these glycoproteins by ordering the placement of sugar molecules on a protein “backbone” called the H antigen. The pattern formed by these sugars determines whether an individual’s blood type is A, B, AB, or O. (In the O type, no sugars are attached to the antigen.)--Harvard Science

D'Adamo hangs much of his theory on the
action of lectins, proteins found on the surface of certain foods that can
cause various molecules and some types of cells to stick together. He
blames lectins for serious disruptions throughout the body, from
agglutination of the blood cells to cirrhosis and kidney failure....

Since most people are unaware of their blood types, let
alone what foods are "evolutionarily inappropriate" for them to eat, it is
reasonable to assume that on most days most people eat the "wrong foods"
for their blood type (e.g., Type O eating wheat, Type A eating meat,
etc.). Thus, according to D'Adamo's theory, most everyone experiences
repeated showers of agglutinated red cells throughout their bloodstream
after most every meal - day after day, month after month, year after year.
If the capillary beds in your heart, lungs, kidneys, brain, eyes, and
other essential organs are subjected to barrage after barrage of
agglutinated red cells, they will eventually begin to clog up. These
micro-areas of diminished blood flow would at first cause scattered, then
more concentrated areas of tissue damage - with eventually many
micro-infarctions scattered throughout these vital structures. The brain,
heart, lungs, kidneys and adrenals would soon be irreparably damaged by
these processes, resulting in potentially fatal outcomes in millions of
people.

Such a syndrome of organ failures due to lectin-induced
micro-infarctions of the brain, heart, kidneys, retinas, and adrenals
would be well known to pathologists and other medical scientists. It would
not be a subtle disease. In the pathology texts, there would be clear
descriptions - complete with photographs taken through high-power, optical
microscopes as well as electron microscopes - of damage from lectin
deposits and blood agglutination in most major organ systems. The
existence and intricacies of such a widespread disease would be as common
knowledge among physicians and cell scientists as atherosclerosis is
today. Yet, I am aware of no such descriptions in the pathologic
literature. No pathologist I know has ever mentioned tissue infarction
from lectin-induced red cell agglutination as a cause of any disease in
humans.

Peter D'Adamo's
reasoning is based on speculative inferences from such "facts" as that type
O is the oldest blood type. It isn't. A is the oldest blood type. Studies in
humans, chimpanzees, and bonobos show that alleles coding for blood type A
are the most ancient version of the ABO blood group. This trait was shared
prior to the evolutionary split between chimpanzees and hominids five to six
million years ago. B blood type split from A about 3.5 million years ago and
O blood type split from A about 2.5 million years ago. From this error
regarding the age of type O, D'Adamo reasons that people with
type O blood should eat the kind of diet the earliest humans ate: one rich
in fat and protein.

"Group A
[D'Adamo erroneously claims] is the
second oldest blood group, appearing around 25,000 - 15,000 B.C., when
larger human settlements first appeared as farming developed."*
From this "fact," D'Adamo infers that people with type A blood should eat
their veggies.

One problem
with D'Adamo's reasoning is that agriculture developed
independently in different parts of the world, the earliest
settled communities didn't develop agriculture for many
centuries in some cases, and the developments weren't all
positive. "A typical hunter-gatherer enjoyed a more varied diet
and consumed more protein and calories than settled people, and
took in five times as much vitamin C as the average person
today" (Bryson: 2010). Worse: "Rice inhibits the activity of
Vitamin A; wheat has a chemical that impedes the action of zinc
and can lead to stunted growth; maize [corn] is deficient in
essential amino acids and contains phytates, which prevent
absorption of iron" (Bryson quoting John Lanchester). According
to Bryson, the average height of people fell by almost six
inches in the early days of farming in the Near East. (Hey, but
it was all organic!) Clearly,
diet matters, but blood type isn't a very good guide to what
diet is right for you.

Group B, D'Adamo
erroneously claims, "emerged
between 15,000 and 10,000 B.C. as tribes migrated from Africa to Europe,
Asia and the Americas and mingled with other populations."*
So, concludes D'Adamo, people with type B blood should eat a "balanced
diet."
In fact: "All human ABO blood types existed as of several million years ago. From the time of the earliest humans, all ABO types existed as hunter-gatherers until the advent of agriculture."*

Of course,
even though there is no plausible scientific connection between
blood type and a proper diet, the advice D'Adamo gives on what
foods to eat or avoid can still be helpful to many people. The
success of his books indicate that the diets he proposes are
probably healthy and safe for most people.

Blood type has little to do with
digestion or body chemistry. If you have blood group A, then you've got A
antigens covering your red cells and anti-B in your plasma. Antigens are
substances that evoke an immune response. Since people in blood group B have
B antigens and carry anti-A in their plasma, type A blood should not be
given to those in Group B, and vice versa. (Group O has neither antigen and
group AB has some of each.) Furthermore, about 85% of us, regardless of
blood type, carry the Rh antigen, while about 15% are Rh negative. About 90
to 95 percent of African Americans and 98 to 99 percent of Asians are
Rh-positive.*
Also, since
pathologist Karl Landsteiner identified the four blood groups early in the
twentieth century, 276 discrete red-cell antigens have been discovered.*

Maybe D'Adamo should have 276 discrete diets, one each
for A+ and A-, B+ and B-, and so on.

Blood type is not totally benign. For many years,
scientists wondered why type O's were more likely than other blood types
to develop stomach ulcers or stomach cancer. In 1993, scientists found
that ulcers were caused by helicobacter pylori, a bacterium which had a
special affinity for one of the unique type O proteins. A geneticist at
Oxford University who checked for other significant associations between
the ABO blood types and the incidence of disease, reported that there were
only seven; the relationships were often weak; and most, like ulcers,
originated somewhere along the digestive tract. If the ABO blood type was
that much of a key, as D'Adamo posits, these relationships would be strong
and plentiful.*

Dr.
Victor Herbert, a hematologist who studied blood and nutrition at New
York's Mt. Sinai Medical Center before his
death, once said of
the theory linking blood type and diet that it is "pure horse manure. It has
no relation to reality. The genes for blood type have nothing to do with the
genes that handle the food we eat."*

Since the diets developed by Peter are
not intrinsically harmful in general, it would be surprising if he couldn't find
many satisfied customers willing to testify on
his behalf. All he has to do is ignore all the cases he didn't help with his
diets to make his case seem stronger than it
really is. Even a broken clock is correct twice a day.

Some of Peter D'Adamo's dietary advice could be harmful,
however.
As Dr. Klaper notes: "despite widespread knowledge that many non-Caucasians
are intolerant of dairy products due to the normal disappearance of lactase
enzymes in their intestinal cells, D'Adamo recommends that 'Type B's of
Asian descent may need to incorporate them (dairy products) more slowly into
their diets as they adjust their systems to them.'" Lactase-deficient
readers who follow this advice are likely to end up with "severe bouts of
abdominal cramps and diarrhea."

Not content with limiting his advice to
matters of nutrition, D'Adamo claims that blood type affects personality and
character. He offers what Dr. Klaper calls "blood type astrology."

In the book [Eat
Right for Your Type], he tells flesh-eating Type O's that they have
a "genetic memory of strength, endurance, self-reliance, daring, intuition,
and innate optimism...", "the epitome of focus, drive...", "hardy and
strong, fueled by a high protein diet" (is he describing a Type O "master
race"?), while he paints the "more vegetarian" Type A as submissive tofu
eaters, "biologically predisposed to heart disease, cancer and diabetes" (p.
97). He labels Type A's with personalities "...poorly suited for the
intense, high-pressured leadership positions at which Type O's excel,"
(p.142), stating that, in pressure situations, people with Type A blood
"tend to unravel" and "become anxious and paranoid, taking everything
personally." Finally, on page 143, he saddles the group with the dark image
of Adolph Hitler, "...a mutated Type A personality." D'Adamo's system seems
to create a "blood type astrology" ("What's your type? O Positive? knew it!
So am I!") that imposes strange, limiting stereotypes on very complex human
beings.*

Many people will no doubt swear by the blood
type diet. For example, a vegetarian who eats a lot of wheat may find that D'Adamo's diet recommendations relieved her digestive problems and a host of
other ailments. She may attribute her former problems to eating the wrong
diet for a type O. However, many people with type O blood are vegetarians or
eat wheat without having any digestive problems. On the other hand, some
people have gluten intolerance and some have colitis. Their doctors probably
advise them not to eat wheat, regardless of blood type.

Link Between Blood Type and Heart Disease Risk Questionable by Walter Jessen
"On NPR’s Science Friday last week, host Flora Lichtman talked with Dr. Eric Topol, a cardiologist and director of the Scripps Translational Science Institute in La Jolla, California, who believes that the “dredging of data” — the practice of searching large volumes of data to find any possible relationship — has resulted in a false conclusion....Indeed, the prospective cohort study did not evaluate the biological processes behind blood type and heart disease risk. In fact, the purpose of the two studies evaluated had little to do with blood type. The Nurses’ Health Study, established in 1976, was designed to investigate the potential long term consequences of the use of oral contraceptives. The Health Professionals Follow-up Study, established in 1986, was designed to evaluate a series of hypotheses about men’s health relating nutritional factors to the incidence of serious illnesses, such as cancer, heart disease, and other vascular diseases. "

Blood types indicate greater risk for cancer "....researchers at Dana-Farber Cancer Institute have confirmed a decades-old discovery of a link between blood type and the risk of developing the disease. Blood-type antigens may also affect the level of inflammatory proteins in a person’s blood. Chronic inflammation has been linked to pancreatic cancer risk. Intriguing as these findings are, they don’t necessarily prove a direct link between blood-type antigens and pancreatic cancer development, the authors assert. It is also possible that the ABO gene is merely a marker for other, nearby genes that are more directly involved in cancer development."

30,000-Year-Old Flour Finding Suggests Cavemen Craved Carbs
"...scientists using optical and electron microscopy have found 30,000-year-old stones
with flour on them at archaeological sites in Italy, Russia and the Czech
Republic....These starch grains suggest food processing of plants and
possibly flour production was common and widespread across Europe at least
30,000 years ago. These carbs might have come in especially handy
when prey was short, the investigators noted."

So, what happened to these Paleolithic people
when they went off the Paleolithic diet?

Dating by
blood type in JapanIn Japan, there is a
widespread belief that blood type determines personality and has
implications for life, work, and love. "The received wisdom is that As are
dependable and self-sacrificing, but reserved and prone to worry.

Decisive and
confident - that is people with type O.

ABs are well
balanced, clear-sighted and logical, but also high-maintenance
and distant.

The black sheep
though seem to be blood group B - flamboyant free-thinkers, but
selfish."